“Hardfacing” is a technique which involves applying a layer of hard material to a substrate for the purpose of increasing the wear and corrosion resistance of the substrate. The use of this technique has increased significantly over the years as industry has come to recognize that substrates of softer, lower cost material can be hardfaced to have the same wear and corrosion-resistance characteristics as more expensive substrates of a harder material.
Hardfacing involves the deposition of a hard layer by welding or thermal spraying. Conventional weld hardfacing is accomplished by oxyfuel welding (OFW), gas tungsten arc welding (TIG), gas metal arc welding (GMAW), shielded metal arc welding (SMAW), flux-cored arc welding (FCAW), submerged arc welding (SAW), electroslag cladding, spray cladding and the like. Plasma transferred arc (PTA) hardfacing and laser beam hardfacing can also be used.
Most prior art hardfacing materials harder than siliceous earth materials are brittle and crack. These hardfacing materials are alloys which belong to a well-known group of “high Cr-irons” and their high abrasive resistance is derived from the presence in the microstructure of the Cr-carbides of the eutectic and/or hypereutectic type. In the as-welded condition, whatever the precautions taken, these hardfacing overlays always show a more or less dense network of cracks.
It would be highly desirable and advantageous to provide a hardfacing alloy composition having a microstructure that has high abrasive resistance and corrosive resistance, and is also capable of being weld deposited without cracks to withstand the conditions of use. Furthermore, it is desirable to form a high chromium welding metal alloy system for use as a hardfacing surfacing on metals components that are subjected to high thermal and mechanical stresses.